The long-term objective of this project is to provide information on neurophysiological and neuropsychological processes that might lead to a better understanding and treatment of Alzheimer's disease. The specific alms are: (1) To extend a previous finding of disruptions in event-related brain activity (CNV rebound) of Alzheimer's patients in central and posterior brain regions to a possible interhemispheric differentiation. This topographical mapping of neurophysiological function may provide a better understanding of regional brain differences based on histopathological findings. (2) To utilize a paradigm that elicits two event-related brain potentials that reflect an early process of selective attention (N1 component) and a later process of information evaluation (P3 component) as a way of evaluating possible differences in abnormalities of different stages of information processing associated with senile dementia. An important aspect of both neurophysiological tests is the combined use of undivided and divided attention paradigms. (3) To provide a neuropsychological assessment of impairment in attention functions with the use of newly developed subject-controlled tasks that optimize the rate of information presentation. (4) To evaluate deficiencies in short-term memory functions associated with senile dementia with the use of both recognition and recall tasks. (5) To test the vulnerability of attention and memory functions of Alzheimer's patients to experimentally-produced distraction. (6) To evaluate the efficacy of two pharmacotherapies, one a conventional treatment (dihydroergotoxine) and one a newly developed nootropic compound (pramiracetam). (7) To test the hypothesis that the heterogeneity of the diagnostic category of Alzheimer's disease might be accounted for by early and late onset of symptoms. An attempt will be made to differentiate these two subgroups with the combined use of neurophysiological and neuropsychological methods.